Lime base grease



Patented July 4, 1950 UNITED STATES PATENT OFFICE LIME BASE GREASE JohnE. Sch'ott, New Stork, and. Eldon L.Arrnstrong, Garden City, N. Y.,assignors to Socony- Vacuum il Gompany, Incorporated, a corpo ration ofNew York No Drawing. Application January 18, 1949, Serial No. 71,554

tions of the type set forth in Carmichael and Hain, U. '8. Patent2,197,263.

The-patent above noted is concerned with the provision'of lime basegreases stabilized against deterioration at relatively high temperaturesby the" incorporation therein of significant amounts, upto about 5%usually, of the calcium salts of m'onobasic fatty acids having not over6 carbonatoms specifically acetic acid.

The-purpose of the'present invention is to provide-agreaseof thischaracter in which certain properties have been improved. One of theproperties thus improvedis that phenomenon known as skin hardening, i.e., a hardening of the surface ofthe grease when exposed to combinationsof moderate temperature and high humidity. Another property improved isthat demonstrated by'what is hereinreferred to as-the Sett test, whereinthe'grease is held for a period of hours at atemperature of 300 F.,which conditions havebeen found generally to-bring about perceptiblehardening of the presently available greases. A third property improvedis that of long time storage stability, it having been notedthatpresentgreases tend to become harder when stored for long periods oftime. While these properties of the present greases are not highlyobjectionable and have not greatly m'ilitated against'wide and readyacceptance of the greases as a premium product, they are nevertheless ofa nature that should be eliminated, if possible, in working toward amore perfect product.

This; invention is based upon the discovery that worthwhile improvementsin such greases can be effected by the replacement of' a portion oftheshort-chain fatty acid modifier by phosphoric acid,- giving rise to aerease'containing a 2 lime soap,.a lime salt of a short chain fattyacid, and, probably; "9, lime salt of an acid of phosphorus.

In general, to arrive at such' modification of the grease, we prefer touse orthophosphoric-acid,

but. wemay use any acidoi phosphorus which, under the conditions ofgrease manufacture will hydrate or hydrolyze with the production oforthophosphoric acid. Such acids are herein in dicated as phosphoricacid;

An-exemplary composition is the following:

Percent (weight) This formulation was compounded in the conventionalcompounding procedure, followed by dehydration, driving off moisturewhile the grease was being stirred. Dehydration is car ried out toiasubstantial'extent; sufiicient to give the grease the desiredstructureand temperature stability.

While the exact reaction into which the 'phosphoric acid enters hasnotbeen studied, it is believed that theresult" of the neutralization ofthe phosphoric acid is formation of a calcium phosphate or" of a calciumcompound of a partial ester'ofphosphoric acid. It suffices to say-thatthe results desiredare'obtaine'd by partial 'substitution of theshort-chain fatty acid with phosphoric acid and such language is usedfor pur- I poses I of definition in the claims.

The improved characteristics obtained-by this formulation may beobserved by consideration of the following table of formulae-and testresults.

TABLE Lime base, acetate modified grease, further modified withphosphoric acid A B O D E Tallow, Per Cent (by Wt.) 13.45.. 13.45..9.85.- 12.50.. 10.1. Oandelilla Wax, Per C 4.00-. 4.00-- 2.93. 3.60-.2.9. Lime Flour, Per Cent. 5.25.- 5.2 3.84-- 4.70-- 3.8. Glycerine, PerCent 2.00.- 2.00-- 1.46.- 1.80.. 1.4. Acetic Acid, Per Cent 3.20--3.60-. 2.63.- 3.30-- 2.7. Phosphoric Acid, Per C 0.80.. 0.40-- 0.29.-0.20-- 0.2. Solar Red Oil, Per Cent 71.30-- 71.30-- 79. 73.90-- 78.9.Ritiodoi Phosphoric Acid to Acetic 1:4- 1:9- 1:9- 1:16. 1:13.

01 Analysis:

Alkalinity, OaO, Per Cent.... 0.5 0.45.- 0.3-- 0.34-- 0.3. SaponifiedFat, Per C 12.2.- 12.40- 9.9.. 12.80.. 10.4. Unsapom'fled Fat, PerCent.-- 0.9.. 1.10.. 0.7.. Water, Per Cent Trace. 0.25. 0.2- 0.50. 0.4.Glycerine, Per C 1.2.- 1.10.- 1.0-. 2.80-- 1.2. tls)ropping Point, ASTM,F--- 500+ 500+ 500+ 500+. es

Pelnetrations, ASTM 77 Unwor 486 258 322 Worke 37 22 294 200 303. SettTest 16 hrs. 300 F. Slightly Hard- Relatively Soit-- No change SlightlyHardened No 'change in conene sis ency. Sett Test 300 F. for 40 doRemained relahours. tively soft. Skin Hardening (Humidity Cab- None in 7days-- No detectable Slight in 72 inet). gardening 48 hours.

. ours. Storage Stability, Days Stored- 890, No harden- 90 No harden-84, No harden- 303, Slight hard- 227, No bard- 440, Slight ing. mg. inening. ening. hardening.

In the above tabulation, the upper portion gives several exemplaryformulae, the middle portion gives analyses of the resulting greases,and the bottom portion gives tests of the resulting greases.

In the tests, the Dropping Point ASTM" and Penetrations, ASTM 77 F. arethe standard tests as specified by the American Society for TestingMaterials.

The Sett Test comprises holding a sample of the grease at the specifiedtemperature for the specified time, and observing the consistency of thegrease after such exposure. I

The Skin Hardening test is conducted by coating a panel of small sizewith the grease, followed by storing in a humidity cabinet at 100 F. and100% relative humidity for a specified period, after which the grease isobserved. The absorption of water vapor by the grease frequently resultsin the formation of a perceptible skin or crust upon the grease.

Both the above tests are related, as accelerated tests, to the actualperformance of the grease in storage, as reported under "StorageStability which merely reports the condition of the grease afterspecified periods of storage under conventional conditions.

It will be observed by reference to the table that the above greasesunderwent no significant change of consistency in the Sett Test, showedno significant skin hardening, and showed no hardening in storage, evenunder periods ranging up towards two and one-half years.

In contrast to this, a conventional acetatemodified line base grease,compounded in accordance with the formula of column A of the table,excepting that no phosphoric acid was used and the acetic acid Wasincreased to 4.00 weight per cent will give the following results. Itwill show perceptible hardening after a sixteenhour Sett Test, it willshow perceptible skin hardening after twenty-four hours of exposure inthe humidity cabinet, and will, normally, both in laboratory andcommercial experience, show a hardening in one year of storage of theorder of about acceptance.

30-40 points of penetration, (sometimes 60 points), gm. load, 77 F.,ASTM method).

These improvements in properties, while small in amount, are worthwhilein that together they define a grease more nearly free of objectionablefeatures than the parent product, even though that parent product hasenjoyed ready and wide In other respects, such as temperature stabilityunder conditions of use, ability to retain oil without separation undernormal conditions of use, as well asduring storage, and the like, theseimproved greases retain the same de-' sirable qualities as exhibited bythe parent grease.

While the degree of modification and improvement obtained is of coursedependent upon the amount of phosphoric acidused, the improve-Q mentsbegin to be present in discernible degree with use of about 0.1% byweight of phosphoric acid in the formulation. The optimum amount ofphosphoric acid appears to be of the order of from about 0.4 per cent byweight to about 0.7 per cent by weight of phosphoric acid in theformulation. Upon the other hand, amounts of phosphoric acid above about2.0 per cent by weight appear to be definitely detrimental, and inhigher amounts destructive. For example, a grease formulated as incolumn A of the table, except using acetic acid 0.8 weight per cent andphosphoric acid 3.2 weight per cent was found to be without any greasestructure at temperatures of about 240 F. and above, and to carry aninsoluble m- This product definitely was not a com-,

of modified lime base greases obtained by the use,

as modifiers, of short-chain monocarboxylic fatty acids of not more thansix carbon atoms. The improvements available by substitution, for aportion of this carboxylic acid, of phosphoric acid exist over the rangeof specified fatty acids.

In general, greases of this type can be achieved,

anew-8o by compounding'together' from --about to about 20 per cent byweight of high molecular weight fia t ae or -a -c n ai ins nf rmi smaterials, from about 0.2,to about 5 percent by wei ht of monocarboxylicfatty acids OfJlQlZQi/BI' ccarbon atoms, the preferred, one being aceticacid, from about 0.1 to about 2 weight per cent of phosphoric acid andcorresponding amounts of hydrated lime or other reactive form of lime,the hydrated lime ranging from about 0.8 to about '7 weight per cent,the resulting grease being dehydrated sufficiently to give the desiredstable structure. In general, the phosphoric acid will be regarded informulation, as a replacement for the low molecular weight fatty acid,and the organic acid be diminished in amount as the amount of phosphoricacid is increased.

We claim:

1. An improved lime base grease composition characterized by stabilityat temperatures in excess of 200 C. and by improved storage stability,comprising lubricating oil, lime soaps of fatty acids in grease formingamounts, a small proportion, sufficient to impart said temperaturestability, of a calcium salt of a monocarboxylic fatty acid having notmore than six carbon atoms, and a small proportion, sufficient to impartsaid storage stability, of a lime salt of phosphoric acid, phosphoricacid having been present in the formulation of said grease in amounts ofat least about 0.1 weight per cent and not exceeding about 2 weight percent of the grease formula.

2. An improved lime base grease composition characterized by stabilityat temperatures in excess of 200 C. and by improved storage stability,comprising lubricating oil, lime soaps of fatty acids in grease formingamounts, a small proportion, sufficient to impart said temperaturestability, of calcium acetate, and a small proportion, sufficient toimpart said storage stability, of a lime salt of phosphoric acid,phosphoric acid having been present in the formulation of said grease inamounts of at least about 0.1 weight per cent and not exceeding about 2weight per cent of the grease formula.

3. An improved lime base grease composition characterized by stabilityat temperatures in excess of 200 C. and by improved storage stability,comprising lubricating oil, lime soaps of higher molecular weight fattyacids in grease forming amounts, a small proportion, sufficient toimpart said temperature stability and not over about 5 per cent, of acalcium salt of a monocarboxylic fatty acid having not more than 6carbon atoms, and a small proportion, sufficient to impart said storagestability, of a lime salt of phosphoric acid, phosphoric acid havingbeen present in the formulation of said grease in amounts of at leastabout 0.1 weight per cent and not exceeding about 2 weight per cent ofthe grease formula.

4. An improved lime base grease composition characterized by stabilityat temperatures in excess of 200 C. and by improved storage stability,comprising lubricating oil, lime soaps of higher molecular weight fattyacids in grease forming amounts, a small proportion, suiiicient toimpart said temperature stability and not over about 5 per cent, of acalcium salt of acetic acid, and a small proportion sumcient to impartsaid storage stability, of a lime salt of phosphoric acid, phosphoricacid having been present in the formulation of said grease in amounts ofat least about 0.1 weight per cent and not exceeding about 2 weight percent of the grease formula.

5. Improved lime base greases characterized by stability at temperaturesin excess of "200 and by improvedstoragestability formed by :compoundingtogether from about 5 to'about' 20-Jper cent of high molecularaweightfatty acid soap forming'materials, from about 0.2 to about 5 per cent ofmonobasic fatty acids of not over 6 carbon atoms, from about 0.1 toabout 2 per cent of phosphoric acid, from about 0.8 to about 7 per centof lime, all by weight, the remainder being lubricating oil.

6. Improved lime base greases characterized by stability at temperaturesin excess of 200 F. and by improved storage stability formed bycompounding together from about 5 to about 20 per cent of high molecularweight fatty acid soap forming materials, from about 0.2 to about 5 percent of acetic acid, from about 0.1 to about 2 per cent of phosphoricacid, from about 0.8 to about I per cent of lime, all by weight, theremainder being lubricating oil.

7. An improved lime base grease composition characterized by stabilityat temperatures in excess of 200 F. and by improved storage stability,comprising lubricating oil, lime soaps of fatty acids in grease formingamounts, a small proportion, sufiicient to impart said temperaturestability, of a calcium salt of a monocarboxylic fatty acid having notmore than six carbon atoms, and a small proportion, sufficient to impartsaid storage stability, of a lime salt of phosphoric acid, phosphoricacid having been present in the formulation of said grease in amounts ofat least about 0.1 weight per cent and not exceeding about 2 weight percent of the grease formula, the resulting grease being dehydrated to adegree sufficient to give high temperature stability.

8. An improved lime base grease composition characterized by stabilityat temperatures in excess of 200 F. and by improved storage stability,comprising lubricating oil, lime soaps of higher molecular weight fattyacids in grease forming amounts, a small proportion, sufficient toimpart said temperature stability and not over about 5 per cent, of acalcium salt of a calcium salt of acetic acid, and a small proportion,sufficient to impart said storage stability, of a lime salt ofphosphoric acid, phosphoric acid having been present in the formulationof said grease in amounts of at least about 0.1 weight per cent and notexceeding about 2 weight per cent of the grease formula, the resultinggrease being dehydrated to a degree sufficient to give high temperaturestability.

9. Improved lime base greases characterized by stability at temperaturesin excess of 200 F. and by improved storage stability formed bycompounding together from about 5 to about 20 per cent of high molecularweight fatty acid soap forming materials, from about 0.2 to about 5 percent of monobasic fatty acids of not over 6 carbon atoms, from about 0.1to about 2 per cent of phosphoric acid, from about 0.8 to about '7 percent of lime, all by Weight, the remainder being lubricating oil, theresulting grease being dehydrated to a degree suflicient to give hightemperature stability.

10. Improved lime base greases characterized by stability attemperatures in excess of 200 F. and by improved storage stabilityformed by compounding together from about 5 to about 20 per cent of highmolecular Weight fatty acid soap forming materials, from about 0.2 toabout 5 per cent of acetic acid, from about 0.1 to about 2 per cent ofphosphoric acid, from about 0.8 to about 7 per cent of lime, all byweight, the remainder bemg lubricating oil, the resulting grease beingde- REFERENCES CITED The following references are of record in thefile'of this patent: 1

UNITED STATES PATENTs Name Date I Carmihfiel r. Apr 16, 1940 Kaufman fiJune 17, 1941 Zimmer Oct. 7, 1941 McLennan Mar. 18, 194']

1. AN IMPROVED LIME BASE GREASE COMPOSITION CHARACTERIZED BY STABILITYAT TEMPERATURES IN EXCESS OF 200*C. AND BY IMPROVED STORAGE STABILITY,COMPRISING LUBRICATING OIL, LIME SOAPS OF FATTY ACIDS IN GREASE FORMINGAMOUNTS, A SMALL PROPORTION, SUFFICIENT TO IMPART SAID TEMPERATURESTABILITY, OF A CALCIUM SALT OF A MONACARBOXYLIC FATTY ACID HAVING NOTMORE THAN SIX CARBON ATOMS, AND A SMALL PROPORTION, SUFFICIENT TO IMPARTSAID STORAGE STABILITY, OF A LIME SALT OF PHOSPHORIC ACID, PHOSPHORICACID HAVING BEEN PRESENT IN THE FORMULATION OF SAID GREASE IN AMOUNTS OFAT LEAST ABOUT 0.1 WEIGHT PER CENT AND NOT EXCEEDING ABOUT 2 WEIGHT PERCENT OF THE GREASE FORMULA.